Far from being the strong character he is often portrayed as being, Macbeth is essentially a weak man; he allows the witches and Lady Macbeth to manipulate him into an act which, if left alone, he would never contemplate, never mind commit.

For it:
If it wasn't for Lady Macbeth and the witches manipulating Macbeth then these crimes would have never been committed.

“All hail, Macbeth! Hail to thee, Thane of Glamis!” first Witch pg.17 Act 1 Sc. 3 Line 51

“All hail, Macbeth! Hail to thee, Thane of Cawdor!” second witch pg.17 Act 1 Sc. 3 Line 52

“All hail, Macbeth! That shalt be king hereafter! Third witch pg.17 Act 1 Sc. 3 Line 53

Quote 1 line 38 – 41 act. 1 Sc. 7 Lady Macbeth to Macbeth
“From this time
Such I account thy love. Art thou afeard
To be the same in thine own act and valor
As thou art in desire?”

Meaning 1 line 38 – 41 act. 1 Sc. 7
“From now on this is what I’ll think of your love. Are you afraid to act the way you desire? Will you take the crown you want so badly, or will you live as a coward, always saying “I can’t” after you say “I want to”?”

Quote 2 line 52 – 59 act. 1 Sc. 7 Lady Macbeth to Macbeth
Did then adhere, and yet you would make both.
They have made themselves, and that their fitness now
Does unmake you. I have given suck, and know
How tender ’tis to love the babe that milks me.
I would, while it was smiling in my face,
Have plucked my nipple from his boneless gums
And dashed the brains out, had I so sworn as you
Have done to this.

what you desire your afraid to admit.

Meaning 2 line 52 – 59 act. 1 Sc. 7
Now the time and place are just right, but they’re almost too good for you. I have suckled a baby, and I know how sweet it is to love the baby at my breast. But even as the baby was smiling up at me, I would have plucked my nipple out of its mouth and smashed its brains out against a wall if I had sworn to do that the same way you have sworn to do this.

the baby that i loved i would have killed it for for

After the witches told Macbeth his untold future he told Lady Macbeth, which then persuaded him to kill Duncan.

The witches were one of the main reasons why Macbeth turned into a selfish, evil man. They revealed their predictions of Macbeth's future

she will do thiese things and stick to what she said but mabeth would say something but not follow through